Semi-automatic telephone-exchange.



C. A. W. HULTMAN. SEMI-AUTOMATIC TELEPHONE EXCHANGE.

APPLICATION FILED MAR.1B,1916- 1,256,322. Patented Feb. 12, 1918.

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SEMI-AUTOMATIC TELEPHONE EXCHANGE.

APPLICATION FILED MAR. I8. 1916.

1,256,322. Patented Feb. 12, 1918.

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C. A. W. HULTMAN.

SEMI-AUTOMATIC TELEPHONE EXCHANGE.

APPLICATION FILED MAR. 18. ms.

1,256,322. Patented Feb.12,1918.

3 SHEETS-SHEET 3- SIIvciIfoz HI cmmm UNITED STATES ATENT SEMI-AUTOMATIC TELEPHONE-EXCHAN GE.

Specification of Letters Patent.

Patented Feb. 12, 1918.

Application filed March 18, 1916. Serial No. 85,119.

scribers lines are connected by means of.

call finders pre-s'electors or the like, is assigned to each operators position and in which the connections are established by means of automatic switches under the control of register or call storing devices which, after having been set by the operator accordingto the member wanted, govern the selective movement of the switches. In semiautomatic systems of this class hitherto known the register devices of each position were usually all arranged in common to all junctions of the corresponding position and, upon a call, an idle one was automatically connected to the calling junction. This arrangement, evidently, requires special switches and circuits for selecting an idle register device and connecting the same to the calling junction.

One object of the present invention is to simplify said circuits and switchin means so as to obtain reliable operation and a quick connection of the register with the junction. To that effect the junctions at an operators position are divided into a number of subgroups each having a register device particularly associated with it. In this arrangement there is, evidently, no selection of idle register devices and the means for connecting up the registers can be made considerably simpler and may consist only of relays in which case the connections are effected instantaneously.

Other features of the invention relate to means for allowing only a certain maximum number of unattended calls to be received simultaneously at an operators position, or in a group of junctions in a system of the kind ust described. In case of a maximum number of one call for instance, all junctions of the positions or groups in question are made inaccessible for further calls when a call is made on one of the junctions the sub-group including the calling junction remaining inaccessible until the connection has been completed while the other subgroup or sub-groups of the position or main group are made availiable for another call as soon as the call has been attended to by the operator.

In case two or more simultaneous calls are allowed as a maximum the arrangement is such that all junctions of a sub-group are made inaccessible when a call is made on one of them all junctions assigned to the operators position being made inaccessible when the maximum number of calls is attained, while, as soon as one call has been attended to by the operator, the junctions of one or more non-engaged subroups are made available for another cal. In this case a simple circuit arrangement may be cbtained by dividing the junctions allotted to an operators position into a number of main groups or sections each comprising a, number of sub-groups and adapted for a maximum number of only one unattended call the number of such selections corresponding to the maximum number of simultaneous calls allotted to each section working independent of the other in the manner above described.

It has been found practical to divide all junctions of an operators position into two sections corresponding to a maximum number of two simultaneous unattended calls each section comprising two sub-groups and the corresponding register devices. The key-board is preferably arranged in common to all register devices of the position but, if required, two key-boards may be provided for each section. When a call is coming in on one junction all junctions of the corresponding section are made inaccessible for further calls and the calling junction is connected to the operators telephone. After having received the number wanted the operator writes it down on the keyboard and operates a starting button where- 'by the key-board is connected to the register device of the sub-group in question which is set according to the number wanted the keyboard being immediately after disconnected from the register and made available for another call. At the same time, the connec'ting operation is started under the control of the register and all junctions of the section in question except those of the engaged sub-group are made available to receive another call. \Vhile the connecting operation is going on a second call may come in on a unction of the other sub-group of the same section or on a junction of the other section which call is attended to in the same way as just described. In the last instance at first all junctions of the section are made inaccessible but as soon as the starting button is pressed down the junctions of the non-enga ed sub-group are made available for another call. Two calls may come in simultaneously, one in each section, but only one can be connected at each time to the operators telephone.

The invention is illustrated in the accompanying drawings in connection with a tele phone exchange system according to the British specification No. 13,302 of 1914, in

which the connections are established by means of large connector switches having a capacity of 10,000 lines. The movable contacts of such switches are preferably arranged to be set to both sides in two principal directions, the subscribers line wires being arranged in four groups with the movable contact carrier in a central position with regard to said groups, as described in British specification N 0. 4,285 of 1915.

Figure 1 showsthe arrangement at the operators position.

Fig. 2 is a circuit diagram of the register or call storing device and the group selector.

Fig. 3 is a circuit diagram of the connector.

The figures illustrate only the numerical selection as the non-numerical selecting operation or the pre-selection is of no importance to the present invention.

A calling subscriber, on lifting his receiver, is automatically connected in any known manner, for instance, by means of first and second pre-selectors with a line leading to a connector or, if the exchange has more than 10,000 subscribers, to a groupselector serving to select the 10,000 group in which the required subscribers line is to be found. In the following it is assumed that the connections are established over such group-selectors. In connection with each selector is arranged a connector finder operating to extend the connection to an idle connector of the 10,000 group in question.

'Each operators position has allotted to it a certain number of junctions j leading from the second pre-selectors to the group-selectors GS. Said junctions are divided into two main'groups or sections PS and PS each comprising two sub-groups SG and 86: Only one unction a, I), c, is shown fully connected up to the operators position. Each operator is provided with a key-board KB, associated with an impulse transmitter IT, Fig. 2. Allotted to each subgroup SG is a register or call storing device 0S, Fig. 2, which by means of a relay RR or RR can be connected to the key-board and its impulse transmitter. Only one register, viz. that one belonging to the sub-group SG of the section PS is shown in the drawing.

The register CS consists of 5 register switches corresponding to the different digits of the subscribers numbers and operated by electromagnets RE R15 RE RE, and BT1 The operation of the register is controlled by an auxiliary switch or register controller 0 having a number of sets of contacts arranged in four contact positions and four sections I, II, III and IV. The contacts of each sections are operated by a separate switch arm and all switch arms are mounted on the same shaft carrying a ratchet wheel operated by an electromagnet OE. The various sets of contacts will be referred to in the following description by designations 1 :2 (i. e. the second of the first section) IVA (i. e. the fourth set of the fourth section) and so on. For the purpose of controlling the connecting operations the register is connected with the calling junction by means of relays R and B, Fig. 2, over a corresponding set of bus-bars S S Fig. 1.

Each group-selector GS has associated with it a number of connector finders CF (three being shown) the contact arms of which are mounted on the same shaft. The number of connector finders corresponding to the number of 10,000 groups.

The impulse sending device by which the control impulses are sent from the connector to the register, comprises contact ribs a, b, Fig. 3, a number of series of contact strips and sliding contacts 8,, S) movable with the contact carrier of the connector. For the salge of space the ribs a and b and the contact strips are drawn in one and the same direction though they must, of course, in the practical arrangement be placed one part horiz'ontally and the other part .vertically.

The group-selectors, connector-finders and the connectors are driven by continuously rotating shafts by means of electromagnetic clutches.

\Vhen the second preselector has reached the selector line marked as disengaged a current flow will be obtained through the whole Winding of the calling relay of the preselector, through the c-line Over the point .2 the contact 300 of the cut-off relay UB through the lamp relay LaR over the indicating bar m through the upper winding of the indicating relay MR the contact 301 on the indicating relay MR and the contact 302 in. the operators microtelephone-jack and to earth. The contact 302 is closed,

when the operator has his microtelephone switched in, but is opened when the'microtelephone is taken away and thus the operators position is marked engaged.

As the resistance of the above-described circuit up to the bar 122, is very small, while MR, has a comparatively great resistance, the bar m,'will obtain such a potential, that no other 2nd speech selector, testing the 0- line belonging to the operators position can be connected to said position. All c-lines connected to m, will be marked engaged as long as the described condition remains. \Vhen MR, is excited, its contact 303 is closed and accordingly the bars m, and m, connected, whereby all the c-lines, connected to both said bars, will be marked engaged. Thus only one call can come in at one time von this half of the key-board, but another call may be received on the second half by closing of the circuit from the c-line of a 2nd preselector over m or m, and through M,R, over a contact in an indicating relay corresponding to MR, and to earth.

When MR, is excited, its contact 30% is also closed, whereby current is obtained over the contact 305-011 the operating relay ER and through the operating relay ER,. Hereby ER, is excited and its contacts 306 and 307 are opened and the contacts 308310 are closed. On account of the disconnection at 306, ER is prevented from being energized and by the closing of 308 and 309 the operators telephone set'is connected over the condensers K and K, with the line bars 25, and 415,. When LaR, was excited and its contact 311 closed, current was obtained from the battery through the lamp La,, 311, the bar Z8 and the contact 307 to earth, which makes the lamp La, light. When now 307 is opened, the lamp La, will lose its constant current, but will instead of that obtain intermittent currents over the contact 310 and the interrupter I, and thus the lamp will burn with a flashing light. WVhen LaR, was excited, its contacts 312 and'313 were also closed, whereby the aand b-lines from the second preselector are connected with the line bars t, and t, and as these as before mentioned, are connected with the operators telephone apparatus by relay ER,, the calling subscriber will obtain speech connection with the operator and can demand the desired number. The operator marks the desired number on the key-board and then presses the starting button SK, that is just opposite the flashing lamp, that is the lamp corresponding to the connection just switched in to the operator. When LaR, was excited, its contact 314 was excited, whereby current was obtained from earth over 314, the bar 1',, the register relay RR, and to the battery. RR, is thus excited and all its contacts are closed. \IVhen now the starting button SK, is pressed down, its contact 315 is at first closed, whereby the current coming in from the second preselector over the c-line, is transmitted over 315 and through UR, to earth. UR, is thus excited and its contact 300 is opened and 316 closed. By the closing of 316, UR, will obtain holding current over the contact z,, so that UR, will remain excited (in spite of the disconnection at 315, when SK, is released) until disconnection takes place after the end of the conversation. UR, has a so great resistance that the calling relay of the second preselector will remain excited and the connection taken by the preselector will still be marked engaged. By the disconnection at 316 the current through LaR, and MR, ceases and these relays will be released. Thereby the talking connection between the calling subscriber and the operator is naturally broken, the lamp La, is cut off, the connection between the bars m, and m, is opened and the operatin relay ER, will be without current. When R, is released and its contact 306 is closed, ER for the second half of the position will be free to be operated and if a call has arrived on this part of the key-board, the subscriber will now by influence of ER be connected with the operators telephone. \Vhen the button SK, was pressed down, its contact 317 was also closed, whereby the following circuit is obtained: earth, 317, the bar 8,, and through the motor M of the impulse machine to the battery. Over the same current contact is also obtained over the contact 318 through RR, to the battery. As before mentioned, RR, was excited when 314 of LaR, was closed and thus RR, will remain excited in spite of the opening of 314 at the same moment when CK, is pressed down. When the motor begins to rotate, the contact 319 is closed, whereby the motor as well as RR, are grounded and will then accordingly remain excited (in spite of the disconnection at 317 when SK,- is released) until 319 again is opened when the impulse machine has rotated one revolution. When the impulse machine begins to rotate, a number of current impulses are obtained through the registeis RE, RE respectively, which impulses correspond to the keys depressed in the switchboard.

The registers are connected through their respective contacts on RR, each with one ring on the impulse machine and as the buttons in the different rows of the key-board will ground the-same number of contact blades in the respective sections of the impulse machine as corresponds to the number of the pressed buttons, the registers will obtain the same number of impulses and thus take up positions corresponding to the buttons pressed down. As the contact 320 of RE was closed at the same moment RE, left its initial position the indicating relay MR, was excited in the same moment whereby its contact 301 was opened and 321 was closed. By this latter connection the lamp La will begin to glow and continues to do so until MR will be currentless, that is until RE returns to its initial position. By the disconnection at 301, the earthconnection for the upper winding of M, R, is broken, which effects that no further subscriber can reach the corresponding part of the right half of the operating board before RE has again reached its normal position, that is before the set of register switche taken inuse is again entirely disconnected. If a second preselect'or when seeking a disengaged connection to a selector passes over the 0- lines comin in to the bar m its calling relay cannot e excited, so long as the disconnection at 301 remains. Thus it has been shown, that a call can simultaneously come in on each of the halves on the key-board, but that only one of these at a time may be switched in to the operators telephone and besides, that when the operator has executed an order for a conversation, no further call can reach the quarter of the operating table, that corresponds to the lastly executed call until the connection is complete. The second quarter of the same half of the position is however marked disengaged at the same moment when a starting button belonging to this second half i pressed. If a call came in for example on some one of the cords -belonging to the bar m while connecting operation takes place on some one of the cords belonging to the bar m that is if the operator has pressed the corresponding starting button, but the registers are still working, then besides a lamp relay corresponding to LaR also MR will be excited on account of the current through its lower winding. Thereby the relays RR and M 11 will apparently be brought in action in the same manner as RR, and MR and by influence of R8,, the impulse machine is switched in to a second set of register switches.

At the same moment the starting button was pressed down, besides 315 and 317, 322 was closed, whereby the following circuit was obtained: earth, 322 and the relays R, and R to the battery. lVhen'R is excited its contact 323 is closed, whereby the two relays will receive holding current over 323, the bar 8,, and 320 of R13 R, and R thus remain excited until the connecting operation is entirely finished. By the disconnections at 324 and 325 of R the calling subscriber is out off and by the closing of 326 and 327 the aand 6- lines in the selector are connected over the bars .9 and 8 respectively with the line relays LR, and LR, (over 166 of the relay V). By the closing of 328 of R the d-line of the selector is over a, connected with the lowest spring of the relay V. By the closing of the contact 329 of R connection will be obtained from the nzeaaea further over the contact 25 of the register switch RE, to the battery, and the selector will thus be made to rotate at the same moment R is excited. By closing the contact 330 of R connection will be obtained from the contact 152 of the. calling relay LyR over the bar 8., to the contact 26 of RE,.

In this specification the contacts specially adapted for the semi-automatic arrangement have been indexed with numbers from 300 and upward, while lower numbers have reference to the preceding description of the full automatic system. As the restoring of the register switches and so on, after they have been adjusted by means of the keyboards takes place in accordance with the same principles as in the full automatic system it has not been considered necessary to here describe these details. Reference is made therefore in applicable parts to the description of the full automatical system. Below will be given only a short account of the succeeding operations. When the impulse machine started to rotate its contact 332 was closed, whereby current was obtained through the operating electromagnet OE of the switch 0 and when 332 is opened after the register switches have been set and the impulse machine has returned to its initial position, the auxiliary switch willaccordingly reach its second position. Through the contact IV22, earth connection is obtained over the contact 25 of RE the bar 8,, 329 of R and through the magnetic clutch MK, and the selector will therefore as indicated above start to rotate. In the usual way impulses from the selector are thereby obtained and these are transmitted over 1:2 through the register RE that is moved step by step, until 25 is opencdwhen the movement of the selector ceases. By closing the contact 26 the relay R in the selector will now be excited in the same way as at the full automatic system, thereby making the connector-finder rotate which continues until a free connector has been found, when Ly R. is excited and the contact taken is marked engaged. I

When It, was excited the following circuit was obtained: earth, 157, 331, 8 and through OE to the battery, and when the current through R, ceases at the same moment the disengaged connector is found, the current through OE will thus be broken and the reverser reaches its third position. The connector now begins to move in the same way as before described for the full automatic system either to the right or to the left. depending upon the position taken up by RE that is: depending upon whether only 0,13 or both 0,15 and V have been excited. As will be seen, V is over H153 connected with the contact 32, and 0 E is over 111:3 (the outer contact) connected with 38. During the movement of the connector, the impulses on the a-, b-, and the (Z-lines will excite RE and R11 and when these two have returned to the normal position, the horizontal motion of the connector will cease. As 0 E in the same moment will be deprived of current, its contact 173 is opened, whereby OE, which during the horizontal motion has been energized, now will be currentless and the auxiliary switch will reach its fourth position. After this the connector begins its vertical motion and continues same until RE has returned to the normal position, when the auxiliary switch again reaches its initial position on account of the disconnection at 173 of O E When 320 of RE is opened, the current through MR ceases, which has the effect that the lamp Lat is extinguished and the upper winding of M,R, is grounded. The corresponding quarter of the operators position, hitherto marked engaged will thereby be made free for a new call from another 2 :nd preselector.

Besides this, a disconnection of the current through R, and R, will be obtained by the opening of 320 of RE and as the relays R, and R now are released, the calling subscriber will be connected over the selector and so on. Already at the same moment when the calling subscriber was connected with a selector, the clearing-signal relay AR was switched in to the aand 1)- branches and the calling subscriber will during the whole time obtain his current feed through this relay.

Vith. the selector is associated a special one-armed auxiliary switch 0 which is mechanically connected with the switch 0 in such manner that it follows the latter step by step until and including the fourth step but which has no electrical function until it reaches the fifth position when it switches in the back-relay BR to the d-line. (This auxiliary switch reaches its fifth position at the same moment when the other returns to its first position.) When the subscribers hang up BR will in the same way as in the full automatic system be energized and its contact 198 will be closed, whereby follows that OE receives a current, that ceases at the same moment when BR is currentless after the connector has been restored to normal position.

When thus the auxiliary switch is thereby moved into its first position, MK and MK will obtain current over the contacts 93 and 94 respectively, and thus the selector and I this is obviously ready for a new call. When said battery-connection on the c-line ceases, UR will be released and LaR, will again be-switched in to the c-line for the receiving of a new call.

The mechanical operating of the connector.

The connector is movably arranged upon a carriage, movable horizontally upon one or more beams, which again are vertically movable on vertical beams.

The clutch electroinagnets M,K M,K and M K are so arranged, that when they are excited they fix clutch rope pulleys or similar arrangements which normally can move freely on their shafts, to the said shafts. These rope pulleys pull said carriage by means of an endless wire in one or the other horizontal or vertical directions according as one or the other clutch electromagnet is energized.

The brakes MB 1 and MB which are operated when the clutch electromagnets are disconnected, only serve the purpose of securing an instantaneous arresting of the carriage or the connector. The mechanical features of the connector are described more in detail in the above-mentioned application #841,966.

I claim- 1. A semi-automatic telephone exchange system comprising an operators position, a group of junctions associated therewith and divided into a number of sub-groups, call storing devices associated one with each sub-group and means for making all junctions of the group inaccessible for further calls when a call is made on one of them.

2. A semi-automatic telephone exchange system comprising an operators position, a group of junctions associated therewith and divided into a number of sub-groups, call storing devices associated one with each sub-group, means for engaging all junctions when a call is made on one of them and means for disengaging a number of junctions as soon as the call has been attended to by the operator.

3. A semi-automatic telephone exchange system comprising an operators position, a group of junctions associated therewith and divided into a number of sub-groups, call storing devices associated one with each subgroup, means for engaging all junctions of the group when a call is made on one of them, means for disengaging all junctions except those of the calling sub-group as soon as the call has been attended to by the operator and means for disengaging the junctions of the calling sub-group when the connection is completed.

4. A semi-automatic telephone exchange system comprising an operators position, a group of junctions associated therewith and divided into a number of sub-groups, call storing devices associated one with each subgroup, means for engaging all junctions of a sub-group when a call is made on one of them and means for engaging all junctions associated with the opera tors position when a certain maximum number of unattended calls are received at the operators position.

5. A semi-automatic telephone exchange system comprising an operators position, a group of junctions associated therewith and divided into a number of sub-groups, call storing devices associated one with each subgroup, means for engaging all junctions of a sub-group when a call is made on one of them,means for engaging all junctions associated with the operators position when a certain maximum number of unattended calls are received at the operators position and means for disengaging a number of junctions as soon as one call has been attended to by the operator.

6. A semi-automatic telephone exchange system comprising an operators position, a

number of junctions associated therewith and divided into a number of main groups each main group being divided into a num-- groups, a call storing device particularly associated with each sub-group and means for allowing only one unattended call to be received at any one time in each main group.

In testimony whereof I afiix my signature in presence of two Witnesses.

CARL AXEL WILHELM HULTMAN.

Witnesses:

FRANK LYON, SALLY J. 03111.12. 

